Design of a torus magnetorheological finishing (TMRF) device for optical manufacturing

To address the growing demand for a diverse range of shapes in optical components for evolving optical systems, this paper introduces a novel torus magnetorheological finishing (TMRF) method. This method harnesses the strengths of both magnetorheological finishing (MRF) and ring tools, thereby achieving ring tool with a guaranteed level of machining stability. Magnetic field analysis is performed in accordance with the Biot-Savart law, and the key excitation parameters are optimized, systematically designed, simulated, and experimentally validated. The design parameters comprise the pole width (w), pole gap (e), pole height (H), and the magnetic field’s influence at the loop section (θmag), and the derived design specifications are sequentially w = 10 mm, e = 2 mm, H = 20 mm, θmag = 180°. The simulation of the magnetic field aligns closely with the theoretical calculations, mirroring the observed change trends from empirical magnetic field tests. For the TMRF under both short and long terms fixed-point polishing, the variations in material volume removal rate were ± 3.0% and ± 10.0%, respectively, and the variations in root mean square (RMS) values at the polishing tool’s base were ± 3.8% and ± 2.0%, respectively. The experimental evidence confirms that TMRF exhibits a stable and highly effective polishing performance. Moreover, the design principles elucidated in this paper offer a significant reference for future research.